Integrated Interpretation of Electrical Resistivity Tomography for Evaporite Rock Exploration: A Case Study of the Messinian Gypsum in the Sorbas Basin (Almería, Spain)
Metadatos
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MDPI
Materia
Selenite Alabastrine Anhydrite Sorbas basin SE Iberia Electrical tomography Seismic Geophysical prospecting
Fecha
2023-01-17Referencia bibliográfica
Pérez-López, A.; García- López, M.; González-Gil, M. Integrated Interpretation of Electrical Resistivity Tomography for Evaporite Rock Exploration: A Case Study of the Messinian Gypsum in the Sorbas Basin (Almería, Spain). Minerals 2023, 13, 136. [https://doi.org/10.3390/min13020136]
Resumen
In this study, we conduct an investigation of the Sorbas Basin (Almería, Spain) on the
Messinian gypsum unit using geophysical prospecting methods. Geophysical electrical resistivity
tomography (ERT) methods were applied to study the subsurface of this gypsum unit, the exploitation
of which could be of interest economically, with different commercial specifications for alabastrine
and selenitic gypsums. For the interpretation of the different ERT images, the data for the surface
geology, borehole cores, and seismic refraction conducted at a point within the ERT profiles were
used. The results obtained from this investigation can be used as a reference for other similar studies
in other regions. It was observed that selenitic gypsum is more resistive than alabastrine gypsum;
therefore, the diagenetic processes of dehydration (anhydritization) and hydration (gypsification)
increase the “percolation” phenomenon through possibly ensuring a greater connectivity of the shale
matrix. Fracturing and moisture can be used to fully determine the resistivity of the purest and most
resistive gypsum, to the point of considerably lowering the resistivity in an entire area affected by
fracturing. The use of different tests with different lengths for the same profile can help one better
understand the structure of the gypsum body in the subsurface, especially when there are shale
intercalations or more- or less-pure levels of gypsum that do not reach a value of a few meters in
thickness, because these thinner levels of a few meters are not defined in the ERT images when the
test is performed at depths of up to 75 m.